fixed exception import.  check for objects being present in the identity map occurs not just  at commit time but also when its logged as "dirty" or "deleted".
fixed exception import.  check for objects being present in the identity map occurs not just 
at commit time but also when its logged as "dirty" or "deleted".


git-svn-id: 655ff90ec95d1eeadb1ee4bb9db742a3c015d499@1049 8cd8332f-0806-0410-a4b6-96f4b9520244

obeattie/sqlalchemy,obeattie/sqlalchemy,obeattie/sqlalchemy